Đề sai, em xem lại đề nhé

1. a. plays b. looks c. wants d. helps

2. a. books b. things c. programs d. rulers

3. a. serious b. symptom c. sauce d. sugar

4. a. horrible b. hour c. hundred d. hold

5. a. touched b. laughed c. talked d. rented

1a

2a

3d

4b

5d

a) Ta có MH//AC \(\left(\perp AB\right)\) nên \(\Delta BMH\sim\Delta BAC\)

\(\Rightarrow\dfrac{BM}{BA}=\dfrac{MH}{AC}\) \(\Rightarrow BM.AC=BA.MH\)

Tam giác ABH vuông tại H có đường cao HM 

\(BA.MH=HB.HA\)     

Tương tự, ta có: \(CN.AB=HC.HA\)

Cộng theo vế 2 hệ thức trên, ta được:

\(BA.MH+CN.AB=HB.HA+HC.HA=HA\left(HB+HC\right)=AH.BC\)

Ta có đpcm.

b) Tam giác ABH vuông tại H có đường cao HM nên \(AM.BM=MH^2\).

 Tương tự, ta có \(AN.CN=HN^2\)

 Do đó \(VT=AM.BM+AN.CN=MH^2+HN^2\)

 Dễ thấy tứ giác AMHN là hình chữ nhật nên \(MH^2+HN^2=MN^2=AH^2\)

 Tam giác ABC vuông tại A có đường cao AH nên \(AH^2=BH.CH\)

 Từ đó suy ra \(VT=BH.CH=VP\)

 Vậy đẳng thức được chứng minh.

 c) Xét hệ trục tọa độ Axy với A là gốc tọa độ, \(Ax\equiv AC,Ay\equiv AB\)

 Khi đó đặt \(B\left(0;b\right)\), \(C\left(c;0\right)\)

 Khi đó phương trình đường thẳng \(BC:y=-\dfrac{b}{c}x+b\)

 \(\Rightarrow\) Phương trình đường thẳng \(AH:y=\dfrac{c}{b}x\)

 Khi đó hoành độ của điểm H chính là nghiệm của pt hoành độ giao điểm của AH và BC: \(\dfrac{c}{b}x_0=-\dfrac{b}{c}x_0+b\)

 \(\Leftrightarrow\left(\dfrac{c}{b}+\dfrac{b}{c}\right)x_0=b\) 

 \(\Leftrightarrow\left(\dfrac{c^2+b^2}{bc}\right)x_0=b\) 

 \(\Leftrightarrow x_0=\dfrac{cb^2}{b^2+c^2}\) 

 \(\Rightarrow y_0=\dfrac{c}{b}x_0=\dfrac{c}{b}.\dfrac{cb^2}{b^2+c^2}=\dfrac{bc^2}{b^2+c^2}\)

 Vậy \(H\left(\dfrac{cb^2}{b^2+c^2},\dfrac{bc^2}{b^2+c^2}\right)\)

 Vì M là hình chiếu của H lên trục Oy \(\Rightarrow M\left(0,\dfrac{bc^2}{b^2+c^2}\right)\)

 Tương tự \(\Rightarrow N\left(\dfrac{cb^2}{b^2+c^2},0\right)\)

 Khi đó \(BM=BA-MA=b-\dfrac{bc^2}{b^2+c^2}=\dfrac{b^3+bc^2-bc^2}{b^2+c^2}=\dfrac{b^3}{b^2+c^2}\)

\(CN=CA-NA=c-\dfrac{cb^2}{b^2+c^2}=\dfrac{cb^2+c^3-cb^2}{b^2+c^2}=\dfrac{c^3}{b^2+c^2}\)

 \(\Rightarrow\dfrac{BM}{CN}=\dfrac{\dfrac{b^3}{b^2+c^2}}{\dfrac{c^3}{b^2+c^2}}=\dfrac{b^3}{c^3}=\left(\dfrac{b}{c}\right)^3=\left(\dfrac{AB}{AC}\right)^3\)

 \(\Rightarrow\sqrt[3]{\dfrac{MB}{NC}}=\dfrac{AB}{AC}\) (đpcm)

Bạn cần trả lời nhiều câu hỏi và tham gia các hoạt động tích cực trên OLM là hack được rồi.

là sao

Help 😭

1. I hope I ___________the exam.

a. will pass b. pass c. will passes d. am passing

2. He’s famous_____________ his invention.

a. of b. about c. for d. on

3. My father will _______________ me to the zoo tomorrow.

a. taking b. to take c. takes d. take

4. He enjoys_____________TV in his free time.

a. watching b. to watch c. watches d. wach

5. She goes swimming________________.

a. everyday b. everydays c. every day d. every Sundays

6. They ____________at home yesterday.

a. were b. was c. are d. is

7. We ______________ some flowers tomorrow.

a. will buy b. buy c. bought d. buying

8. Look! He _____________to music.

a. is listening b. listens c. are listening d. listen

9. _____________he eats breakfast, he will be hungry.

a. If b. Unless c. If not d. Because

10. If you don’t eat, you ____________hungry.

a. will b. are c. will be d. is

11. After supper, he went on_____________________ his homework.

a. do b. doing c. did d. does

12. I will tell him about it as soon as he_________________ back.

a. comes b. will come c. come d. to come

13. It was too late, so I had to go home_____________________ a hurry.

a. with b. on c. in d. for

14. He is working hard now, but he used to__________ very lazy.

a. was b. being c. is d. be

15. His father often makes him__________________ up early.

a. get b. to get c. gets d. getting

16. I like to travel _______________ a train.

a. on b. with c. through d. by

17. When you __________________ her, you will agree with me about it.

a. meet b. have meeting c. are meeting d. would meet

18. Look! Someone ______________________.

a. is coming b. are coming c. come d. coming

\(#FallenAngel\)

1. I hope I ___________the exam.

a. will pass b. pass c. will passes d. am passing

2. He’s famous_____________ his invention.

a. of b. about c. for d. on

3. My father will _______________ me to the zoo tomorrow.

a. taking b. to take c. takes d. take

4. He enjoys_____________TV in his free time.

a. watching b. to watch c. watches d. wach

5. She goes swimming________________.

a. everyday b. everydays c. every day d. every Sundays

6. They ____________at home yesterday.

a. were b. was c. are d. is

7. We ______________ some flowers tomorrow.

a. will buy b. buy c. bought d. buying

8. Look! He _____________to music.

a. is listening b. listens c. are listening d. listen

9. _____________he eats breakfast, he will be hungry.

a. If b. Unless c. If not d. Because

10. If you don’t eat, you ____________hungry.

a. will b. are c. will be d. is

11. After supper, he went on_____________________ his homework.

a. do b. doing c. did d. does

12. I will tell him about it as soon as he_________________ back.

a. comes b. will come c. come d. to come

13. It was too late, so I had to go home_____________________ a hurry.

a. with b. on c. in d. for

14. He is working hard now, but he used to__________ very lazy.

a. was b. being c. is d. be

15. His father often makes him__________________ up early.

a. get b. to get c. gets d. getting

16. I like to travel _______________ a train.

a. on b. with c. through d. by

17. When you __________________ her, you will agree with me about it.

a. meet b. have meeting c. are meeting d. would meet

18. Look! Someone ______________________.

a. is coming b. are coming c. come d. coming

1. I hope I ___________the exam.

a. will pass b. pass c. will passes d. am passing

2. He’s famous_____________ his invention.

a. of b. about c. for d. on

3. My father will _______________ me to the zoo tomorrow.

a. taking b. to take c. takes d. take

4. He enjoys_____________TV in his free time.

a. watching b. to watch c. watches d. wach

5. She goes swimming________________.

a. everyday b. everydays c. every day d. every Sundays

6. They ____________at home yesterday.

a. were b. was c. are d. is

7. We ______________ some flowers tomorrow.

a. will buy b. buy c. bought d. buying

8. Look! He _____________to music.

a. is listening b. listens c. are listening d. listen

9. _____________he eats breakfast, he will be hungry.

a. If b. Unless c. If not d. Because

1. I hope I ___________the exam.

a. will pass b. pass c. will passes d. am passing

2. He’s famous_____________ his invention.

a. of b. about c. for d. on

3. My father will _______________ me to the zoo tomorrow.

a. taking b. to take c. takes d. take

4. He enjoys_____________TV in his free time.

a. watching b. to watch c. watches d. wach

5. She goes swimming________________.

a. everyday b. everydays c. every day d. every Sundays

6. They ____________at home yesterday.

a. were b. was c. are d. is

7. We ______________ some flowers tomorrow.

a. will buy b. buy c. bought d. buying

8. Look! He _____________to music.

a. is listening b. listens c. are listening d. listen

9. _____________he eats breakfast, he will be hungry.

a. If b. Unless c. If not d. Because

10. If you don’t eat, you ____________hungry.

a. will b. are c. will be d. is

11. After supper, he went on_____________________ his homework.

a. do b. doing c. did d. does

12. I will tell him about it as soon as he_________________ back.

a. comes b. will come c. come d. to come

13. It was too late, so I had to go home_____________________ a hurry.

a. with b. on c. in d. for

14. He is working hard now, but he used to__________ very lazy.

a. was b. being c. is d. be

15. His father often makes him__________________ up early.

a. get b. to get c. gets d. getting

16. I like to travel _______________ a train.

a. on b. with c. through d. by

17. When you __________________ her, you will agree with me about it.

a. meet b. have meeting c. are meeting d. would meet

18. Look! Someone ______________________.

a. is coming b. are coming c. come d. coming

1. I hope I ___________the exam.

a. will pass b. pass c. will passes d. am passing

2. He’s famous_____________ his invention.

a. of b. about c. for d. on

3. My father will _______________ me to the zoo tomorrow.

a. taking b. to take c. takes d. take

4. He enjoys_____________TV in his free time.

a. watching b. to watch c. watches d. wach

5. She goes swimming________________.

a. everyday b. everydays c. every day d. every Sundays

6. They ____________at home yesterday.

a. were b. was c. are d. is

7. We ______________ some flowers tomorrow.

a. will buy b. buy c. bought d. buying

8. Look! He _____________to music.

a. is listening b. listens c. are listening d. listen

9. _____________he eats breakfast, he will be hungry.

a. If b. Unless c. If not d. Because

\(\dfrac{3}{2\text{x}4}+\dfrac{3}{4\text{x}6}+...+\dfrac{3}{48\text{x}50}\)

\(=\dfrac{3}{2}\text{x}\left(\dfrac{2}{2\text{x}4}+\dfrac{2}{4\text{x}6}+...+\dfrac{2}{48\text{x}50}\right)\)

\(=\dfrac{3}{2}\text{x}\left(\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{6}+...+\dfrac{1}{48}-\dfrac{1}{50}\right)\)

\(=\dfrac{3}{2}\text{x}\left(\dfrac{1}{2}-\dfrac{1}{50}\right)=\dfrac{3}{2}\text{x}\dfrac{24}{50}=\dfrac{36}{50}=\dfrac{18}{25}\)

\(\dfrac{2}{3}A=\dfrac{2}{2\times4}+\dfrac{2}{4\times6}+...\dfrac{2}{48\times50}\)

\(\dfrac{2}{3}A=\dfrac{4-2}{2\times4}+\dfrac{6-4}{4\times6}+...+\dfrac{50-48}{48\times50}\)

\(\dfrac{2}{3}A=\dfrac{4}{2\times4}-\dfrac{2}{2\times4}+\dfrac{6}{4\times6}-\dfrac{4}{4\times6}+...+\dfrac{50}{48\times50}-\dfrac{48}{48\times50}\)

\(\dfrac{2}{3}A=\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{6}+...+\dfrac{1}{48}-\dfrac{1}{50}\)

\(\dfrac{2}{3}A=\dfrac{1}{2}-\dfrac{1}{50}\)

\(\dfrac{2}{3}A=\dfrac{12}{25}\)

\(A=\dfrac{12}{25}\div\dfrac{2}{3}\)

\(A=\dfrac{18}{25}\)

x+(x+1)+(x+2)+...+(x+10)=88

=>11x+(1+2+...+10)=88

=>11x+55=88

=>x+5=8

=>x=3